The present invention relates to new derivatives of urea and of thiourea based on organopolysiloxanes which are insoluble in water and organic solvents The new derivatives have various applications in industry. The polymeric ureas are primarily precursors for corresponding carbodiimide derivatives which, for their part, can be used as insoluble reagents in chemical synthesis. In contrast thereto, the polymeric thioureas are used especially as metal adsorbing agents. Methods of preparing and using the new products are other aspects of the present invention.
Reagents based on organic polymers are increasingly used in chemical synthesis and applications, e.g. as ion exchangers, catalytic carriers, metal adsorbing agents, enzyme carriers or carriers of functional groups. Examples are described in Chem. Ing. Tech., Vol. 51, no. 7, p. 728 (1979), in Chem. Rev., vol. 81, p. 557 (1981) or in Annu. Rep. Prog. Chem, Sect. B 83, p. 283 (1986) publ. (1987).
When these compounds are used, the organic polymer matrix sometimes does not meet the requirements placed thereon of thermal and mechanical stability, inertness to chemical attacks, accessibility of the functional groups and solubility in the solvent used. These difficulties could be avoided if inorganic polymer systems such as e.g. silica gel, aluminum oxide or titanium dioxide were used as carriers Such systems exhibit the advantages of a fixed, rigid structure, lack of swelling capacity, high resistance to temperature and ageing, insolubility and ready accessibility of the functional groups present. It is known with respect to the foregoing that inorganic carriers have already been provided with suitable functional groups, as is described e.g., in DE-OS 24 33 409. However, a significant disadvantage of these known products is the low functionality.
According to a new concept of the hydrolysis and polycondensation of suitable organofunctional silanes, corresponding organofunctional polysiloxanes have been obtained in the meantime which exhibit a high functionality on the one hand and on the other hand good matrix properties as in the case of inorganic polymers. A survey about such polymers is presented in Angewandte Chemie, vol. 98, p. 237 (1986).